Hydroquinone

CAS#: 123-31-9

Synonyms: 1,4-benzenediol; p-dihydroxybenzene; hydroquinol; quinol.

Uses: Photographic developer (except color film); dye intermediate; inhibitor; stabilizer in paints and varnishes, motor fuels, oils; antioxidant for fats and oils; inhibitor of polymerization; skin hyperpigmentation (banned in EU and USA).

Hazard: This material is very toxic; the probable oral lethal dose for humans is 50-500 mg/kg, or between 1 teaspoon and 1 ounce for a 150 lb. person. It is irritating but not corrosive. Fatal human doses have ranged from 5-12 grams, but 300-500 mg have been ingested daily for 3-5 months without ill effects.  Death is apparently initiated by respiratory failure or anoxia.